1. Field of the Invention
The present invention relates to electrical test equipment, and in particular to an electrical safety compliance test instrument having an improved operator interface.
The electrical safety compliance test instrument of the invention includes a number of improvements designed to simplifying set-up and testing procedures, in order to reduce the risk of operator error and to ensure accurate test results. The improvements utilize a softkey controlled display screen capable of displaying a complete safety test instruction set or set of test parameters, and/or a complete set of test results, to provide the following interactive display functions or features:
a pause/prompt function that causes prompts to be displayed during a pause, in order to facilitate operator reconfiguration of the equipment during testing;
an autocalibration alert function that alerts the operator when the instrument is due for scheduled calibration; and
a security function that enables the operator to select from among a plurality of security level options
a more flexible menu structure that enables set-up of additional tests performed by plug-in test instrument modules.
2. Description of Related Art
Electrical safety compliance test equipment has become increasingly sophisticated or complex, both to meet the requirements of different agencies responsible for safety compliance testing, and also because of the availability of improved microprocessor based controllers which enable a single tester to perform multiple tests based on pre-programmed instruction sets. As a result, demands on the operator of the equipment have also increased. In order to perform the multiple tests that might be required for a particular product, the operator must not only correctly program all of the numerous test parameters for each of multiple steps, but also must, during testing, correctly connect and then reconfigure the connections between the test equipment and the device undergoing the tests. Often, the same equipment is used to test different types of products, each requiring different sets of tests or testing procedures, or to test products for shipment to different countries with varying test requirements. Because many of the tests are performed at voltages in excess of 1000 volts, incorrect connections can present a serious safety hazard to the operator or bystanders, while improper test set-up or interpretation of the test results can result in the shipment of defective products and hazards to consumers.
An example of the trend toward greater test instrument sophistication is the multiple function dielectric withstand tester described in U.S. Pat. No. 6,054,865, assigned to Associated Research, Inc. of Lake Bluff, Ill., which is capable of performing at least five different types of tests. The tests, which include high voltage AC and DC dielectric withstand tests, insulation resistance tests, AC ground bond tests, and DC continuity tests, all require different connections between the tester and the device under test, and therefore a highly skilled operator. In addition, the Associated Research multiple function dielectric withstand tester has the capability of being linked to additional safety testers of different types, further complicating test set-up and interpretation.
Another example of a tester capable of performing different types of tests with multiple test configurations is the line leakage tester disclosed in U.S. Pat. No. 6,011,398, also assigned to Associated Research, Inc. This tester has the capability of running multiple tests to simulate different potential hazards that might be faced by a user of the product being tested, and like the Associated Research multiple function dielectric withstand tester, also includes external link capabilities.
To simplify test set-up and minimize risk of operator error, both of the Associated Research testers provide an integrated menu-driven user interface for setting-up multiple pre-programmed test sequences. For example, the operator interface of the electrical safety compliance test instrument illustrated in FIG. 1, which is identical to the instrument illustrated U.S. Pat. No. 6,054,865, includes a keypad 1 made up of a plurality of pre-assigned function keys 2 and a numeric keypad 3, various LED indicators 4,5 and an LCD display screen 6 capable of displaying interactive menus through which test parameters such as voltage and current levels, test duration, and ramping times, may be preprogrammed or set for each of the types of tests that the instrument is capable of carrying out, as well as an on/off switch 7, start button 8, reset button 9. Also included on the front panel of the illustrated multifunction dielectric withstand test instrument are respective high voltage, current and return jacks 10,11,12.
By providing integrated, menu driven operator interfaces, the test instruments described in the Associated Research patents, including the test instrument illustrated in FIG. 1, reduce the chance of operator error and thereby offer significant safety and convenience advantages over conventional non-interactive instrument displays. Nevertheless, the operator interfaces of the two testers, as well as those of other safety compliance test instruments, still place relatively high demands on the operators, with consequent hazards to both the operator and end-users of the product being tested.
In order to eliminate any possible source of operator error, it has been proposed in U.S. Pat. No. 5,861,882 to completely automate the process of test configuration, using software-based switches to switch between multiple test instruments and an icon based interactive test set-up and control display. While this approach has the advantage of ease-of-use, the icon based control is designed to be implemented on a central computer linked to separate test instruments and is not suitable for implementation through a display integrated into the front panel of a single instrument, the separate test instruments being connected via a common bus to the central computer and via a single pre-configured interface to the device under test. The configuration of the interface to the device under test is not specifically described in U.S. Pat. No. 5,861,882, but rather is presumed to be constant, with no provision for automatic switching or re-connection of test probes, or for programming of individual test instruments to cooperate with the main control program and accept the appropriate test commands. To the contrary, as explained in the abstract of U.S. Pat. No. 5,861,882, the test instrument of this patent seeks to dynamically reconfigure the test set up for different tests without hand rewiring or loading of other test programs, thereby both increasing the complexity of the system and in practice greatly limiting the number of different types of tests that can be performed with a particular instrument. This lack of provision for reconfiguration of instrument to device under test connections makes the system described in this patent impractical for many safety compliance testing applications.
Unlike the operator interface described in U.S. Pat. No. 5,861,882, which is designed to control separate test instruments connected by a common bus to a pre-configured connection to the device under test, the present invention concerns an operator interface integrated into a single multiple function test instrument. In the context of single instrument operator interfaces, it is of course known to provide displays that provide multiple lines of text as well as graphics, but none of these single-instrument displays address the above-described concerns related to electrical safety compliance testing.
An example of a prior text/graphic display capable of displaying large amounts of information is the medical diagnostic instrument display disclosed in U.S. Pat. No. 5,056,059. While the display screen disclosed in this patent could be included in a multiple function safety compliance test instrument, however, the software that controls the display is not suitable for use in a safety compliance tester because of the limited number of probe configurations and types of tests that can be controlled by the instrument, and the higher level of training required to operate the instrument.
Another type of instrument with an operator interface that utilizes a sophisticated text/graphics display is the communications line test device disclosed in U.S. Pat. No. 5,808,920. The test device disclosed in U.S. Pat. No. 5,808,920 is arranged to enable input and interpretation of digital communications protocols, however, and therefore does not require the multiple test lead configurations or high voltages of safety compliance test instruments.
Also of interest by way of background are voltage-current multimeter displays, such as the one disclosed in U.S. Pat. No. 6,064,372, which eliminates the need for multiple buttons by including a touch screen, and oscilloscope displays, such as the one described in U.S. Pat. No. 5,321,420, which is of particular interest because it includes a softkey control rather than a scrolling or purely graphical display. While multimeters and oscilloscopes both perform numerous types of electrical tests, however, neither utilizes pre-programmed test sequences of the type included in the above-described safety compliance testers, and thus the operator interfaces used in such electrical testers are not suitable for use in safety compliance testers.
Those skilled in the art will appreciate that the displays disclosed in the above-mentioned patents are both more sophisticated than those of conventional safety compliance testers, and yet are not suitable for use in such testers because of the lack of provision for pre-programmed test set-ups, and other features unique to safety compliance testing. The present invention, on the other hand, occupies a middle ground between the multiple instrument graphical user interface described in U.S. Pat. No. 5,861,882 and the scrolling displays integrated into the Associated Research test instruments disclosed in U.S. Pat. Nos. 6,054,865 and 6,011,398, or the test instrument disclosed in U.S. Pat. No. 5,101,160, which like the displays described in the Associated Research patents, includes a scrolling test mode alphanumeric display (col. 7, lines 7-12) and a code key lockout feature (col. 7, lines 47-50). In particular, without requiring a separate computer and graphical user interface as in U.S. Pat. No. 5,861,882, the present invention address problems unique to electrical safety testing that cannot be addressed by the limited displays of conventional instruments, including the following:
Because of the limited size of the conventional safety compliance test instrument display screen, only one step or set of parameters can be presented at one time, making it difficult and relatively time consuming to input and verify an entire test setup, and to read the results of a test.
Although a number of currently available testers provide for pre-programming of multiple test set-ups, it is still necessary to manually reconfigure connections to the device under test, during which improper connections can occur.
Improper test results and possible hazards to the operator can result from failure to calibrate the instrument regularly.
While prior safety compliance test instruments include lockout features for preventing unauthorized use of the instrument, the conventional lock-out arrangements lack the flexibility to permit access to selected test set-ups but not others, or to limit changes to certain parameters or features.
In summary, despite the importance of electrical safety compliance testing and the availability, in other contexts of suitable displays, no safety compliance instrument to date has addressed such concerns as the need to provide operator prompts that ensure proper manual reconfiguration by the operator of test set-ups during testing, timely calibration of the instrument, or the ability to select from among a plurality of security level options. What is needed is an operator interface including a display suitable for integration into a safety compliance test instrument that provides clear instructions on carrying out a test, including instructions on reconfiguration of the connections to the device under test, as necessary, and that ensures that the instrument is properly calibrated and ensures access only to operators qualified to perform particular tests greatly enhances the safety of the testers.
It is a accordingly a first objective of the invention to provide a safety compliance test instrument having an improved operator interface that minimizes risk of operator error during set-up and running of multiple tests, and of errors in reading or interpreting test results.
It is a second objective of the invention to provide a safety compliance test instrument having an improved display enabling verification at a glance of entire test sequences, sets of test parameters, and test results.
It is a third objective of the invention to provide a safety compliance test instrument having an improved display that minimizes risk of operator error by providing prompts during pauses for operator reconfiguration, instructions on re-positioning or change of test leads, and on interconnection of multiple test instruments of different types.
It is a fourth objective of the invention to provide a safety compliance test instrument that reduces risks associated with miscalibration by providing a warning that scheduled calibration is required.
It is a fifth objective of the invention to provide a test instrument with enhanced security features, including the ability to allow an operator to not only select a password to access system set ups, but also to enable restriction of users to partial recall of test set ups or only the test and reset functions, allowing better control and monitoring of tests and test results.
It is a sixth objective of the invention to provide a test instrument having a more flexible menu structure that enables set-up of additional tests performed by plug-in test instrument modules
These objectives of the invention are achieved, in accordance with the principles of a preferred embodiment of the invention, by providing a safety compliance test instrument with a large display, soft key controls, a pause/prompt feature that enables display of instructions for re-configuring or changing test leads during pauses between tests, a calibration warning feature that warns the operator a predetermined time before calibration of the test instrument is required, and an enhanced security feature that enables input and display multiple lockout levels.
The pause/prompt, calibration warning, and enhanced security features of the preferred embodiment of the invention are each preferably accessed through softkey-controlled submenus that permit entry, respectively, of messages to be displayed during pauses in execution of control programs, a calibration alert toggle setting and number of days before calibration that the alert is to appear, and a security activation toggle setting, password entry, and security level toggle setting.
In a particularly preferred embodiment of the invention, the test instrument is a multifunction safety compliance tester of the type disclosed in U.S. Pat. No. 6,054,865, which is capable of performing insulation resistance and ground circuit tests as well as high voltage AC and DC dielectric withstand or hipot tests, and which is further arranged to receive plug-in test instrument modules that permit additional tests to be performed by the safety compliance instrument, the menu structure permitted by the preferred display enabling set-up of the additional tests performed by the plug-in test instrument modules through a single integrated menu-driven control input.
Although a particular type of safety compliance test instrument is described in detail herein, those skilled in the art will appreciate that the principles of the preferred embodiment of the invention may be applied to line leakage testers, run testers, and a variety of other test instruments capable of running multiple pre-programmed test sequences requiring multiple test lead configurations.